> And, compared to existing means-tested aid, UBI reduces the disincentive to outside income.

Important point.

Especially people currently on disability are actively disincentivized from doing any amount of work. Worse, they're even disincentivized to do volunteer work out of terror that someone might report them as able-bodied and they lose their benefits, even if they are legitimately disabled and merely trying to contribute the tiny amount that they can.